The present invention relates to a filtration system for an aquarium which is particularly intended for use with salt water fish, commonly referred today as "reef tanks". In particular, the present invention relates to a highly simplified and efficient, self-contained, gravity fed, wet/dry filtration system which is intended to allow one to maintain a reef tank with a high number of marine aquatic specimens.
Various aquarium filtration systems are, of course, well known and in wide use for both fresh water and salt water tanks (e.g., U.S. Pat. Nos. 4,036,756 and 3,313,421). In both aquariums for home and professional use, it is well known to use a filtering system for removing impurities and waste material from the aquarium water, which comprises a separate filtering system external to the aquarium tank which has a siphon housing assembly and a filter-holding tank assembly. In this system, water is siphoned from the tank into the filter assembly, filtered, and then returned to the tank via a pump and further siphon. While generally satisfactory, these filter assemblies are rather cumbersome and unsightly, requiring the use of siphons which necessitate the provision of holes in the tank cover. In addition, priming the pumps of such filtering systems has proven to be a messy and inconvenient operation and, at best, it often involves a complicated and difficult procedure. A variety of in-tank bottom filtration systems are also known (e.g., U.S. Pat. Nos. 3,294,239 and 4,817,561), but these are generally inefficient, difficult to use and ineffective.
There are also many references to marine biological filtration systems. For example, Brock, U.S. Pat. No. 3,774,766, discloses a two-compartment filter assembly, the first being provided with a drip pan feed and an unsubmerged filter bed holding "splitrock" upon which aerobic bacteria are situated. Katz, U.S. Pat. No. 3,835,813, discloses a balanced system for purifying aquatic media, which comprises three filtration systems, namely, biological filtration, mechanical filtration and algae propagation. Smith, U.S. Pat. No. 4,002,566, discloses a system for purifying aquarium water which includes a filtration system, including a perforated plate for supporting a bed for establishing and maintaining a bacterial culture which cleans the aquarium water flowing therethrough.
However, here too, various disadvantages are found in these prior art devices when it is intended to use the same in conjunction with particularly small salt water or reef tanks and/or to maintain large numbers of marine aquatic life. For example, they generally are impractical by size and/or design for use with small volumes of water, i.e., 5.5, 10 or 20 gallon tanks. They are cumbersome to use (use of siphons, priming, etc.) and they generally do not provide sufficient filtering to support a high bio mass (i.e., number) of aquatic life. In fact, to the best of applicant's knowledge, there is no in-tank filter system available which affords a biological ecosystem for the long term maintenance of marine specimens in a small tank.